extend the abstract syntax API

src/runtime/haskell/tests/basic.gf

@@ -1,8 +1,10 @@
 abstract basic = {
 
-cat N ;
+cat N; S ;
 
-fun Z : N ;
-    S : N -> N ;
+fun z : N ;
+    s : N -> N ;
+
+fun c : N -> S ;
 
 }

src/runtime/haskell/tests/basic.hs

@@ -3,4 +3,10 @@ import PGF2
 
 main = do
   gr <- readPGF "tests/basic.pgf"
-  runTestTTAndExit (TestCase (assertEqual "abstract names" "basic" (abstractName gr)))
+  runTestTTAndExit $
+    TestList [TestCase (assertEqual "abstract names" "basic" (abstractName gr))
+             ,TestCase (assertEqual "abstract categories" ["Float","Int","N","S","String"] (categories gr))
+             ,TestCase (assertEqual "abstract functions" ["c","s","z"] (functions gr))
+             ,TestCase (assertEqual "abstract functions by cat 1" ["s","z"] (functionsByCat gr "N"))
+             ,TestCase (assertEqual "abstract functions by cat 2" ["c"] (functionsByCat gr "S"))
+             ]